U.S. Pat. Nos. 8,167,073 and 7,594,557, which are incorporated herein by reference in entirety, disclose a suspension assembly for a snowmobile that rotatably supports a closed-loop track in the rear tunnel of the snowmobile and also supports both vertical and horizontal travel of the closed-loop track during suspension system travel. The suspension assembly includes at least one elongated ground contact that supports rotational travel of the closed-loop track, and at least one swing arm angularly disposed in the closed-loop track and having a front end portion pivotably coupled to the rear tunnel and a rear end portion coupled to the at least one ground contact. In the preferred arrangement, a front resilient member is arranged to bias against displacement between the chassis and the at least one ground contact during suspension assembly travel, and a rear resilient member arranged to bias against displacement between the chassis and the swing arm during suspension assembly travel. A tensioner couples the rear portion of the swing arm to the at least one ground contact. The tensioner is extendable and retractable during movement of the suspension assembly to maintain the closed-loop track at a generally uniform tension during assembly movement.
U.S. Pat. Nos. 7,128,180 and 6,926,108, which are incorporated herein by reference in entirety, disclose a rear suspension system for a snowmobile that includes a plurality of adjacent closed-loop tracks disposed in a rear tunnel of the snowmobile. Each of the plurality of adjacent closed-loop tracks are rotatably driven by a drive system. One of a plurality of independent suspension assemblies is disposed in each closed-loop track and the plurality of independent suspension assemblies articulate independently of each other during travel of the rear suspension system.